Ophthalmological analysis systems for measuring a topography of a cornea are sufficiently known and are used in different versions, for instance for measuring the cornea or for determining astigmatism. Furthermore, central and peripheral radii of curvature of the cornea can be measured, which can subsequently be utilized for fitting a contact lens. Here, so-called keratometric analysis apparatuses also serve, amongst other things, to determine a keratoconus and to calculate an intraocular lens. By means of a measurement of a topography of the cornea, it becomes possible to describe a surface progression of a corneal surface, and thus, for instance, to determine a keratoconus. In particular with a keratoconus, there is the problem that it can only be accurately diagnosed after having developed. Often, at an early stage of said eye disease, the symptoms are initially attributed to astigmatism. Thus, it is only possible to accurately determine a keratoconus being at hand by means of an analysis of a corneal surface as well as of a corneal thickness or a posterior corneal surface. Currently, a possibility for early diagnosis of a keratoconus in the phase of development, without symptoms being obviously recognizable, is not known.
Regardless of the above-described keratometric method, it is generally known that, due to a cardiovascular activity of a living being or a person, an intraocular pressure of an eye of said person experiences a very small change. Corresponding to a pulse rate which is conditioned by a heart rate or to an alternating blood pressure change, an intraocular pressure of the eye is increased and reduced at substantially regular intervals. This is caused by the corresponding blood pressure increase inside the head, via which a force is applied on the eye. Said effect of the change in the intraocular pressure can, for instance, be measured with a so-called Pascal tonometer.
A Pascal tonometer comprises a tonometer head which has a concave shape, and which rests against a cornea, as well as an integrated electronic pressure sensor, with which an ocular pulse amplitude or a change in the intraocular pressure as a result of a cardiovascular activity can be measured. In this way, effects, conditioned by properties of the cornea as well as of the ocular pulse amplitude, on the measurement of the intraocular pressure can be eliminated, whereby the intraocular pressure can be measured very accurately. It is disadvantageous that this is an invasive measurement method. In the case of a measurement of the intraocular pressure with a non-contact tonometer, however, a measurement result is affected by the cardiovascular activity or an ocular pulse amplitude. Thus, a change in the intraocular pressure leads to a change in a topography of the cornea which is also very small. This disturbing effect of the cardiovascular activity which affects the measurement result of a tonometer measurement is not taken into account in the case of a measurement with a keratometer, since here, only a topography or radii of curvature are measured, and the very small change in the topography is not essential for the keratometer measurement.